Laminated gear pump



NOV. 7, 1944. A UNGAR ETAL 2,362,106

LAMINATED GEAR PUMP Filed April 21, 1941 4 Sheets-Sheet l INVENTORS Jami 5 A. 04 642. BY IMP/l F. Kaila.

ATT RNEYS Nov. 7, 1944. a. A. U-NGAR ET AL LAMINATED GEAR PUMP Filed April 21, 1941 4 Sheets-Sheet 2 Nov. 7 1944. can A. UNGAR ET AL.

LAMINATED GEAR PUMP Filed April 21, 1941 4 Sheets-Sheet 5 Nov. 7, 1944. UNGAR ET AL 2,362,106

LAMINATED GEAR PUMP Filed April 21, 1941 4 Sheets-Sheet 4 Patented Nov. 7, 1944 LAmNATED GEAR PUMP Gustave A. Ungar, New Rochelle, and Joseph F. York, N. Y., assignors, by direct Keller, New

and mesne assignments to Equl-Flow Inc., New

York, N. Y.,

a corporation of New York Application April 21, 1941, Serial No. 389,634

' 12 Claims.

This invention relates to pumps, and more particularly to gear pumps.

The primary object of our invention is to generally improve gear pumps. A more particular object is to reduce the manufacturing cost of gears for such pumps, this preferably being done by building up the gears out of stamped laminations, thus eliminating the conventional slower methods of cutting the gear teeth.

A further object is to maintain the laminations compressed together in face to face relation. In straight spur gears it is possible to hold the laminations together by inserting rivets not only in the hub area but also through the individual teeth, thereby producing reasonably uniform face to face contact at a slight additional cost. To clamp the gears at the hub only is likely to produce spreading at the teeth. Helically displaced laminations cannot be riveted through the teeth and furthermore solidly clamped laminations in staggered displacement do not permit of the rotation of adjacent meshing laminations because of interference and consequent locking. In our co-pending application Serial No. 385,618 we have provided the holding together of the laminations by fluid pressure, thereby permitting the laminations to move away from each other sufficiently to prevent interference. In accordance with an important feature and object of our present invention, the laminations are pressed or bonded together, but in the meshing zone the requisite side clearances to permit free rotation are provided by suitable slight depressions in the faces of the laminations or by the interposition of thin spacing or separating washers between the laminations.

Another object of our invention is to obtain a solid gear unit from laminations held or bonded together in intimate face to face contact.

Still another object of our invention is to provide a construction suitable for economical quantity production by effecting the joining together of the laminations by utilizing using the spacers as the bond between laminations.

Still another object of our invention is to provide a gear structure made from stamped laminations as they come off the press without further finishing or trimming before assembling the laminations into a gear unit.

Still another object of our invention is to obtain most of the benefits of helical gearing without the usual expense of making helical teeth, and without the disadvantage of axial thrust, nor the cost of double helical gears. For this purpose the successive laminations are stepped or rotatably displaced to form an approximate helical gear. In this construction, there is no axial thrust because the individual laminations are thin spur gears. The slight angular displacement of the laminations also eliminates trapping of liquid between the meshing teeth of the individual pairs of laminations since the liquid trapped is enclosed between the meshing teeth of one pair of laminations and is in communication with similar spaces of trapped liquid in the adjacent pairs of lamination until the spaces finally communicate either with the intake or the discharge port. As long as the angular displacement of the end laminations is not such as to permit a short circuit or communication between the intake and the discharge ports, there will be no danger of leakage. Since there is no trapping, there is consequently no necessity for providing for artificial leakage to avoid the hydraulic shock which is a consequence of trapping. This method of rotatably displacing laminations may also be used to obtain rotors for screw pumps. The features of the invention are applicable to internal as well as external gear pumps.

Still another object of our invention is to obviate other limitations of conventional helical gearing due to the interrelation of normal pitch, helix angle, desired diameter, lead and face. The use of staggered spur gear laminations permits of producing almost any desired gear face with the same diameters by merely adding laminations. The rotative displacement of the individual laminations can be also modified up to the limit where the tooth edges would no longer overlap, thereby introducing leakage.

Still another object of our invention is to provide a structure for the efilcient, inexpensive and silent transmission of power through gears with the possibility of utilizing standard gear laminations in staggered relation for a wide range of transmitted torque by merely modifying the number of laminations in the gear units used.

To the accomplishment of the foregoing general and such other more specific objects as will hereinafter appear, our invention consists in the gear pump elements and their relation one to the other as hereinafter are more particularly described in the specification and sought to be defined in the claims. The specification is accompanied by drawings, in which:

Fig. 1 is a section through a spur gear pump taken in the plane of the line l-I of Fig. 2;

Fig. 2 is a section through the spur gear pump taken in the plane of line 2-2 of Fig. 1;

Fig. 3 is an enlarged fragmentary section through a part of a gear tooth, and is explanatory of a detail;

Fig. a is an enlarged fragmentary .section through a part of a gear tooth of a modification of the invention;

Fig. 5 is an enlarged fragmentary section through a part of. a gear tooth of another modification of the invention;

Fig. 6 is a section through a modified pump having angularly displaced laminations in the plane of the line 6-5 of Fig. 7;

Fig. 7 is a section taken in the plane of the line 'l-l of Fig. 6;

Fig. 8 is an enlarged. isometric fragmentary view of the displaced laminations and spacers, and is explanatory of a detail;

Fig. 9 is a fragmentary section of a driven gear, similar to that shown in Fig. I;

Fig. 10 is an enlarged isometric fragmentary view of a modification of the invention shown in Figs. 7 and 8 respectively;

Fig. 11 shows a section of a pump with axial fiow it is a section taken approximately in the planes of the lines I I-l i of Fig. 12,

Fig. 12 is a section taken, in the plane of the line I2-I2 of Fig. 11.

Fig. 13 is an enlarged isometric fragmentary view of a modification of the invention shown in Fig. 7, and

Fig. 14 is an enlarged fragmentary developed surfaceview of a modified gear of the invention shown in Fig. 7.

Referring to the drawings and more particularly to Figs. 1, 2, 3, and 5, the embodiment of my invention there shown comprises a casing I2 closed by an end cover H and rotatively receiving a driving shaft I6 which is journalled in housing I2 as well as in cover Id. The pump housing I2 (Fig. 2) is provided with main pumping ports 38 and 40. A driving gear l8 which is keyed to shaft I6 by means of key I! comprises a set of stacked laminations, shown more clearly in Fig. 3. These laminations 20 represent the gear faces and their edges 26 thereof are chamfered to provide artificial clearance so as to reduce difiiculties by fluid trapping, the laminations 22 forming the body of the gear. They are separated by thin spacers 24 the latter having the same profiles as the laminations 20 and 22. In connection with varying the material'of which the laminations which constituted, the thickness of these spacers will be up to about .003" ifvthey are of copper, which material may act as a brazing bond between steel laminations, up to .010" if fiber or plastic spacing material is employed and even heavier if it is desired to make them from elastic inserts such as natural or synthetic rubber. The driven gear 28 is similarly made up of a set of stacked laminations, and held together as the laminations of driving gear I8. The driven gear 28 is rotatively mounted on its support shaft 30 which is held with a press fit in casing I2 and slipped into the hole 3| in cover I4 when the pump is assembled.

The laminated gear illustrated in Fig. 3 employs laminations generally produced by machining, die-casting or molding while that shown in Fig. 4 would be representative of stamped laminations from sheet material such as steel, brass, fiber, etc., the stampings being substantially used as they come off the press without removing the rounded corners and the sharp fins resulting aseaioc from the shearing action of the die. The stampings will be rounded at one edge 28 and feathered at the opposite edge 29 as indicated. The spacer 32 is interposed between adjacent laminations which are stacked in the same direction in which they came oil the press. The tooth profile of spacer 32 is preferably slightly smaller than the tooth profile of the laminations.

Those rounded edges 28 provide passages for trapped liquid, while chamfer 29' is provided at thei opposite face to assist in providing trapping re e Fig. 5 illustrates an alternative gear type made up of somewhat heavier laminations 32' separated by spacers 34 which only extend to the bottom of the gear teeth, leaving small gaps 36 between the laminations. These gaps provide bypass space for trapped heavy liquid in addition to piermitting free rotation of the meshing laminat ons.

Referring now to Figs. 6-10 of the drawings, the pump there shown comprises a main housing 52, closed by means of cover plate 54. The driving shaft is indicated at 66 joumalled in the hearing 58 of cover 541 as well as in housing 52.

The driving gear consists also of laminations S0, keyed to shaft 56 by means of a key 62. The laminations are separated by thin spacers 6G. The driving gear differs from those previously described in that the successive laminations are rotatably displaced or stepped relative to one another, the consecutive tooth edges forming helices. This arrangement is more clearly shown in Fig. 8 and it should be observed that the amount of the relative angular shift for instance of the laminations 60 and 60' is less than the angular width of the tooth edge or land. The spacers are interposed between laminations 60 and 60' and it will be seen that the outline of the tooth profile of spacer 64 corresponds substantially to the axial projection of an area corresponding to the overlap of the teeth of laminations 60 and 60'. In other words, spacer 64 corresponds to the area of contact between two adjacent angularly displaced laminations. Provided the outside diameters of spacers G4 are the same as those of the laminations 80, 60, they will form a continuous seal reaching from one end of the gear to the other end since laminations and spacers are pressed or bonded together to form a complete unit and no leakage between laminations is therefore possible even if the side profiles of the spacer teeth do not extend to the tooth profiles of the meshing gear teeth.

As .a matter of fact it will be desirable to keep the tooth profiles of the spacers below the meshing gear tooth profiles in order to avoid any possible meshing interference. The thickness of spacers 64 is very slight and just sufiicient to provide free rotation of the meshing teeth. Where copper spacers are employed to provide the bond for copper brazing, about .003 will be ample and when under pressure while brazing, the actual thickness will be reduced to less than .002". The profile of the spacer tooth has to be determined so as to prevent flowing out over the laminated gear profiles under heat and pressure. Overflow at the outside diameter can of course be removed by grinding. It should be noted that the free rotation of the displaced laminations could also be accomplished by making the thickness of the laminations equal to that of lamination 66 or 68 (Fig. 8) plus the thickness of spacer 64 (Fig. 8) and by providing a facial depression in the laminations as deep as the thickness of spacer 6'3 and 2,se2,1oo 3 equalling in width the rotative displacement of the tooth profiles of two consecutive laminations. Such depressions might be produced by a coining operation on stamped or'machined laminations and in die cast or molded laminations, they could be provided for in the casting or molding dies.

One embodiment of a laminated gear for the gear pump illustrated in Fig. 7 is shown in Fig. 13. The laminations I80, I80, I80" have flat faces I82, I82, I82" and the faces I84, I84, I84" have slight depressions I86, I88, I88". The edges I88, I88, I88" of faces I84, I84, I84" must not project beyond edges I90, I90, I90" of faces I82, I82", I82' so as to prevent interference of meshing laminations. Face I82 of the extreme left hand lamination I80 and face I94 of the extreme right hand lamination I82 provide the'fiat outside'faces of each gear unit.

In Fig.1! is shown an outside developed view of the outside of a laminated gear unit. The tooth tips or lands 2I4 and 2 of the outside laminations 200 and 202 and the tooth tips 2I8, 2I8', 2I8" of the inner laminations 288, 208', 208" form a continuous cylindrical sealing strip along the entire width of the gear not interrupted by any of the slight facial depressions 204 and 208 on the inside faces of the outside laminations and by the slight depressions 2I0, 2I0', 2I0", etc., in the right hand faces of the inner laminations 208, 208', 208" and by the slight depressions 2I2, 2I2, 2I2 in the left hand faces of the inner laminations. The tooth tips or lands 220 and 222 of the outside laminations 200 and 202, and the tooth tips 224, 224', 224" etc. also form a continuous cylindrical sealing strip along the entire width of the gear. Facial depressions 204, 288, 2| 0, 2I0, 2-I0" etc. and 2I2, 2I2, 2I2" extend sufflciently along the faces of the'laminations' to permit free rotation of the lamination of the mating gear without side interference which would result between gear laminations without such depressions, owing to thickness variations resulting from manufacturing tolerances in the thickness of the laminations. Even with absolute uniformity in thickness, there would be surface interference in the meshing zone. The outlineof these facial depressions is similar to depressions I88, I88, I88" etc. illustrated in Fig. 13.

The driven gear 10 is similarly made up of laminations separated by thin spacers I2. The laminations are also displaced relative to each other, so as to mesh freely with the laminations of driving gear 80, the tooth edges of consecutive laminations of the driven gear thereby forming helices having turns opposite to those of the helices formed by the tooth edges of consecutive laminations of the driving gear.

As illustrated in Fig. 7 the laminations of the driven gear are held in correctly spaced relation by means of the spacers 12 which are bonded along their entire surfaces to the laminations. The shape of the tooth profiles of the spacers is similar to those illustrated in Fig. 8 for the driving gear.

In the form shown in Figs. 6 and 7, the driven gear laminations are made from steel, and they are held together by brazing of the spacers I2. In order to provide the greatest simplicity of design and consequent cost and weight economy, the shaft extensions I4 are brazed to gear unit I0 by means of copper spacers 18 which have the same profiles as spacers I2.

The outside diameters of the extensions I4 are I0. Gear 18 and extensions I4 after brazing form one solid unit and the extensions I4 provide the shafts which are journalled in bore 18 of the cover and in extension 80 of easing bore 82 for the driven gear I0.

It will be readily seen that the arrangement of the thin spacers 84, I2 and I8 permits the two gear units to mesh without any interference fiom the adjoining laminations which are simultaneously in mesh, even allowing for slight variations due to commercial tolerances for the thickness of the gear laminations.

In Fig. 9 an alternative construction is shown of the driven gear unit. Here the laminations 84 are stacked face to face against each other and they are mounted on a shaft or pin 88 to which they are keyed by means of key 88. The extension pieces 90 (only one shown in Fig. 9) and the laminations are clamped together by means of nuts 92. This construction is preferably used where non-metallic laminations are desired for the driven gear, such as reinforced phenol plastie, to reduce noise to a minimum.

the same as the outside diameter of driven gear 78 It will also be clearly seen from Fig. 9 that the clearance spaces provided by the spacers 84 give unimpeded passage to the driven laminations 84 when meshing with the laminations of driven gear 80.

Fig. 10 shows a method to build up the gears from stepped laminations made by stamping, using them in the condition as they come from the press made from stampings without having the rounded and finned edges removed.

Here the laminations 92 shows the rounded edges at 94 and the finned edges at 98. Spacers 98 are interposed between the untreated laminations and their thickness should be slightly more than the projection of the finned edge 98, so that in applying pressure and heat as in brazing, the laminations will not touch, thereby providing the requisite axial meshing clearance. The tooth profiles of spacers 98 will preferably be substantially smaller than the axial projection of the overlap of the laminar teeth. As shown in Fig. 10, the outside diameter of the finished gear unit has been subjected to a machining operation so as to present an uninterrupted tooth edge along the entire length of the gear.

The pump housing 52 (Fig. 6) is provided with main pumping ports I 00 and I02.

The invention is applicable to internal as well as to the external gear pumps described and it is adaptable to gear type pumps with axial flow of the fluid pumped. A pump of the last named type is illustrated in Figs. 11 and 12.

Referring to those figures the driving gear H2 in this particular case has two teeth H4 and rlneshes with a driven gear II8 having two teeth Gear I I2 has a profile consisting of cylindrical portions I20 and I22 and of the tooth profiles I I4 which in turn are partly made up of involute or uniform velocity meshing curves I24-I26 which mesh with corresponding involute or uniform velocity meshing curves I 28I30 of teeth II8 of the driven gear H8. The remaining tooth profile I28-I32 of driven tooth profile H4 is a curve which will generate a corresponding rolling contact curve I30I34 on driven gear I I8, when both gears are rotated with uniform angular velocity. The remaining portions of the profile of the driven gear II8 are circular portions I34I38 which pass the circular portions I32-I38 of teeth II4 with a slight constant clearance while the driving gear H2 and driven gear II 8 rotate at uniform angular velocity. The circular portions I28-I89 of the driven gear H8 pass the circular portions MIL-I28 of the driving gear II2 with a slight constant clearance, while the driving and driven gears rotate at uniform angular velocity.

The gears rotate in cylindrical bores I42 and I44 of the main body or casing I46. Suitable endcovers I48 and I60 are provided.

The driving gear H2 is built up of laminations keyed to the driving shaft I52 by means of key I64. The driven gear H8 is similarly built up of laminations keyed to the driven shaft I66 by means of key I58. Both the driving and the driven shafts are suitably journalled in bearings provided in endcovers I48 and I68 respectively and appropriate shoulders I68 and I62 are provided on shafts I62 and I66 respectively in order to carry the axial'thrust by means of thrust faces I64 and I88 respectively, provided on endcover I48.

The laminations of both the driving gear I I2 and of the driven gear II6 are rotatively displaced against their adjacent laminations, the rotative displacements of the driving and driven gears being in opposite directions.

In order to provide uniform driving relations between the driving and driven gears, the rotative angular displacement of two adjacent laminations must be equal to or preferably be less than the angle of gear action of the involute or uniform meshing velocity gear profile portions I24-I26 of the driving gear and I28- I38 of the driven gear. The remaining profile portions of the driving and driven gears rotate past each other not in driving engagement but they pass one another with a small but constant clearance thereby insuring satisfactory sealing action.

The pump body I46 is provided with pumping ports I68 and I10 at opposite ends connecting to the end portions I12 and H4 respectively of the cylindrical bores I42 and I44.

The free meshing of driving and driven laminations can be provided by any of the different gear constructions illustrated in Figs. 8, 9, 10, 13, 14 and it is therefore unnecessary to elaborate upon them.

Suffice it to state that the largest profiles of it into chamber I14 and from there into outlet port I18.

Disregarding leakage losses the volume delivered during a single revolution of driving gear H2 is represented by the cross sectional eightshaped area of the intersecting cylindrical bores I42 and I44, less the cross sectional areas of v gears H2 and H6 multiplied by the pitch of the and internal type and also to screw type pumps.

The provision of axial clearances in the meshing areas of the laminations results in operation free from friction. There is no end thrust owing to the employment of spur teeth only, and the tendency of axial shift and variations of end clearances prevalent in ordinary gear pumps is reduced by the axial stabilizing action of the gear laminations passing by each other with definite fluid or liquid cushions between them which prevent surface contacts.

The circumferential displacement of the laminations in approximate helical form has many advantages such as improved mechanical meshing with less noise, and a substantially constant rate of delivery from the pump, that is from the sum of t e deliveries of the individual laminations. The variations in delivery of a same time.

the spacers employed between the laminations of driving gear II2 are delimited by the axial projection of two overlapping adjacent laminations as indicated by profile I48, I24, I26, I32, I82, II4 and the extreme profile of the spacers of driven gear II6 are delimited by the profile I38, I28, I26, I31, I36, I86 representing the axial projection of two overlapping adjacent laminations.

The pumping action of the driving gear II2 and driven gear II6 requires that there be sumcient laminations to complete at least one pitch of the screw formed by the tooth edges of the displaced consecutive laminations. To reduce leakage losses there should however be a multiple of complete pitches of the screw formed by the tooth edges of consecutive laminations. In Fig. 12 the number of complete pitches is three. The gears having two teeth each the resultant screws will be double thread screws. 7

The cooperation of the two gears rotating in opposite directions as indicated by arrows A and B in a casing which surrounds them with minimum clearance produces a piston action which draws the liquid in through port I68 and chamber IIZ advances it axially and finally discharges single lamination are equalized by proportionate variations of the other laminations. Also, the elimination of trapping of liquid between the teeth of v meshing individual laminations, there being communications from one to the next and ultimately to either the intake or to the discharge port but at no time to both ports at the It should be understood that the total angular displacement of the laminations 01 external or internal spur type pumps must be limited so as to prevent a short circuit from the inlet to the outlet ports. Furthermore, the displacement of the individual laminations must not be such as to prevent an uninterrupted tooth edge along the entire face of the gear.

The angularly displaced laminated pump has many advantages over the conventional type with helical gears such as absence of end thrust, reduced gear separating forces since the effect of the helix angle does not exist, the possibility of substituting h'elical type laminated gears for spur gears without the limitations imposed by helical gears due to the interrelation of normal pitch, helix angle, diameter and lead, the laminations permitting rotative displacement within any desired helical lead. There is the possibility therefore of changing the face width within wide ranges with the same laminations by merely adding laminations and modifying the angular advance. Among other advantages is the greatly reduced manufacturing cost of stamped laminations as they come off the press, bonded togather through spacers, which may in themselves provide the bond between successive laminations, either as solder or brazing between metallic laminations or as adhesive plastic, acting as a bond between non-metallic or metallic laminations.

The particular advantage of reduction of noise is attained with laminated gears due to the breaking up of a solid ringing gear mass into smaller parts. A further noise reduction is attained by the employment of non-metallic spacers clamped between metallic gear laminations.

The arrangement of laminations in intimate contact either by pressure or by surface bonds makes this gear construction also eminently suitable for the efficient, economical, uniform and silent transmission of power through gears with helically displaced laminations. It will be readily seen that with laminations of a certain size it is possible to manufacture gears of a wide range of torque capacities by merely increasin the number of laminations to any desired practical extent.

It will also readilybe seen that the manufacturing costs of laminated gears whether for pumps or for general power transmission will be materially lower than those of gears manufactured by the existingmethods of regular or precision gear production, as long as it is possible to produce stampings, die castings or molded plastics in sufficient quantities to warrant the cost of suitable production dies or molds. Where extreme accuracy of production is necessary, such as for high pressure or air pumps, a shaving operation, added to the stamping operation is necessary. This however reduces the normal stamping radii and feather edges and consequently diminishes the amount which has to be removed from the surfaces of the laminations by grinding so as to produce sharp edges. In certain applications the irregular stamping edges will be sharpened and made uniform by suitable coining operations.

For extreme accuracy of molded or die-cast lami-- nations, a shaving operation will usually be usually in order.

The bonding together of stamped steel laminations by means of brazing the inserted copper spacers provides a very economical method of quantity production of gears especially when the shaft end pieces are brazed on at the same time. A suitable tubular fixture will permit of stacking laminations and spacers in the required helical displacement by the provision of helical guide lips. The end pieces, laminations and spacers are clamped together, placed into an electric brazing furnace preferably in a hydrogen atmosphere and brazed into a solid unit. The outside diameter of the unit is then finished, preferably by centerless grinding.

Suitable bonding methods for non-metallic laminations or spacers by pressure or by heat will also provide laminated gear units with the necessary characteristics of unimpeded meshing.

The invention may be applied to fluids of a liquid or gaseous nature, to motors as well as'to pumps and to the transmission of power.

The laminations may be made from any material suitable for gears and particularly of such a nature which will produce laminated shapes by rapid production methods such as stamping, shaving, broaching, die casting, molding and the like. It should be noted also that elastic materials such as rubber are also suitable for the laminations and the employment of non elastic spacers between the elastic laminations will provide friction free meshing, since spacers of sufficient thickness permit elastic deformation of the gears in the meshing area without side interference.

It will be apparent that while we have shown and described our invention in several preferred forms, many changes and modifications may be made in the structures disclosed without departing from the spirit of the invention as sought to be defined in the following claims.

We claim:

1. A gear pump comprising a casing, pumpkag;

ports in said casing, a driving shaft, a driving gear constituted of laminations keyed to said driving shaft in rotatively displaced or stepped relation, a driven gear meshing with said driving gear, shaft means rotatively supporting said driven gear, said driven gear being constituted of laminations stepped to mesh with said driving laminations, means to hold the laminations of each of said gears in close fluid tight face to face contact, the meshing areas of the side faces of adjacent laminations having shallow local depressions to permit unimpeded passage of the meshing gear teeth of said laminations, without interrupting the fluid tight contact between the faces of adjacent laminations.

2. A gear pump comprising a casing, pumping ports in said casing, a driving shaft, a driving gear constituted of laminations keyed to said driving shaft in rotatively displaced or stepped relation, a driven gear meshing with said driving gear, shaft means rotatively supporting said driven gear, said driven gear being constituted of laminations stepped to mesh with said driving laminations, the rotative displacement of the laminations of said gears being less than the width of the tooth edge, means to hold the laminations of each of said gears in close face to face contact, the meshing areas of the side faces of adjacent laminations having shallow depressions to permit unimpeded passage of the meshing gear teeth of said laminations.

3. A gear pump comprising a casing, pumping ports in said casing, a driving shaft, a toothed driving gear built up of laminations keyed to said driving shaft, a toothed driven gear meshing with the said driving gear, said driven gear being built up of laminations arranged to mesh with corresponding laminations of said driving gear, shaft means to rotatively support said driven gear, means to hold the portion, outside of the actual meshing zone, of the side faces of adjacent laminations of each of said gears together in fluid tight contact between successive teeth, said contact extending from the inside diameter to the outside diameter of the tooth profiles of said laminations, and clearance means in the side faces of adjacent laminations of sufficient transverse extent and depth to permit unimpeded passage of the laminations of the mating gear, the transverse extent of said clearance means being limited so as not to interrupt the liquid tight contact between the side faces of adjacent laminations.

4. A gearpump comprising a casing, pumping ports in said casing, a driving shaft, a toothed driving gear built up of laminations keyed to said driving shaft, a toothed driven gear meshing with the said driving gear, said driven gear being built up of laminations arranged to mesh with corresponding laminations of said driving gear, shaft means to rotatively support said driven gear, means to hold the side faces of adjacent laminations of each of said gears together in fluid tight contact, said contact extending from the inside diameter to the outside diameter of the tooth proflles of said laminations, and clearance means in the side faces of adjacent laminations of sufficient transverse extent and depth to permit unimpeded passage of the laminations of the mating gear, the transverse extent of said clearance means being limited so as not to interrupt the liquid tight contact between the side faces of adjacent laminations, the mating tooth surfaces of the driving and driven gears being generated from appropriate tooth curves with generating lines parallel to the gear axes.

5. A gear pump comprising a casing, pumping ports in said casing, a driving shaft, driving gear built up of laminations keyed to said driving shaft in rotatively displaced or stepped relation, the mating tooth surfaces of the driving gear being generated from appropriate tooth curves with generating lines parallel to the gear axis, a toothed driven gear meshing with said driving gear, said driven gear being built up of laminations, stepped to mesh with said driving laminations, the mating tooth surfaces of the driven gear being generated from appropriate tooth curves with generating lines parallel to the gear axis, shaft means to rotatively support said driven gear, means to hold the side faces of adjacent laminations of each of said gears together in fluid tight contact, said contact extending from the inside diameter to the outside diameter of'the tooth profiles of said laminations, and clearance means 7, in" the side faces of adjacent laminations of sufficient transverse extent and depth to permit unimpeded passage of the laminations of the mating gear, the transverse extent of said clearance means being limited so as not to interrupt the liquid tight contact between the side faces of adjacent laminations.

6. A gear pump comprising a casing, pumping ports in said casing, a driving gear built up of laminations keyed to said driving shaft in rotatively displaced or stepped relation, a driven gear meshing with the said driving gear, the tooth surfaces being generated from suitable profiles with generating lines parallel to the gear axes,

the tips or lands of the teeth consisting of circular portions of a radius equal to the gear outside diameter, shaft means to rotatively support said driven gear; said driven gear being built up of laminations stepped to mesh with said driving laminations, the rotative displacement of the laminations ofsaid gears being less than the circular width of the tip or land of the tooth, means to hold the side faces of adjacent laminations of each of said gears in close contact and shallow depressions located in the meshing zone in the side faces of adjacent laminations of sufllcient transverse extent and depth to permit unimpeded passage of the laminations of the mating gear, the transverse extent of said clearance means being limited so as not to interrupt the liquid tight contact between the side faces of adjacent laminations, the area of the said shallow depressions being substantially equal to the areas enclosed between the leading edges of the tooth profiles of adjacent displaced laminations between the trailing edges of the tooth profiles of adjacent displaced laminations.

'7. A gear comprising co-axially stacked thin stamped laminations, the said laminations being faced in the same direction in which they were stamped from sheet material and being rotatively displaced or stepped in relation to each other, shallow depressions located in the meshing zone of the side faces of adjacent laminations, the said shallow depressions being at least equal to the areas uncovered in the end faces of each lamination by a rotatively displaced adjacent lamination means to hold said laminations in circumferentially fixed relation to each other and means to keep said laminations in face to face contact.

a toothed 8. In a gear assembly, a driving and a driven gear, each constituted of a plurality of rotatively displaced laminations, the laminations of one gear being stepped to mesh with the corresponding laminations of the other gear, the

meshing areas of the side faces of adjacent laminations having shallow depressions eflective to eliminate interference in the meshing areas between the side faces of laminations of the driving gear and the side faces of the laminations of the driven gear.

9. In a gear assembly, a driving and a driven gear, each constituted of a plurality of rotatively displaced laminations, means to hold the laminations of each of said gears in close face to face contact so as to produce a substantially solid gear from such laminations, the meshing areas of the end faces of adjacent laminations having shallow depressions to permit unimpeded passage of the meshing gear teeth of said laminations.

10. A gear pump comprising a casing, pumping ports in said casing, a driving shaft, a driving gear comprising a plurality of laminations keyed to said driving shaft, a driven gear meshing with said driving gear and comprising a plurality of laminations rotatively carried in said casing, a shaft rotatively supporting said driven gear, said laminations forming solid gears each.having a plurality of mating or meshing tooth sections helically displaced from each other, each mating or meshing tooth section being separated from its adjacent tooth section by an intermediate non-mating thin disc portion, substantially corresponding in profile configuration to the area enclosed by the leading ,and trailing tooth profiles of adjacent mating or meshing tooth sections which it separates.

11. A gear pump comprising a casing, pumping ports in said casing, a driving shaft, a driving gear comprising a plurality of laminations keyed to said driving shaft, a driven gear meshing with said driving gear and comprising a plurality of laminations rotatively carried in said casing, a

' shaft rotatively supporting said driven gear, said laminations forming solid gears each having a plurality of mating or meshing tooth sections helically displaced from each other, each mating or meshing tooth section being separated from its adjacenttooth section by an intermediate non-mating thin disc portion, at least equal to the area enclosed by the trailing and leading tooth profiles of adjacent mating or meshing tooth sections which it separates, but not extending so far as to permit direct fluid passage between consecutive teeth of each tooth section.

12. A gear pump comprising a casing, pumping ports in said casing, a driving shaft, a drivin gear comprising a plurality of laminations keyed to said driving shaft, a driven gear meshing with said driving gear and comprising a plurality of laminations rotatively carried in said casing, a shaft rotatively supporting said driving gear, means to hold said laminations in close face to face contact, the meshing areas of the side faces of adjacent laminations having shallow depressions to permit unimpeded passage of the meshing gear teeth of said laminations and effective to eliminate interference between the side faces of meshing laminations.

GUSTAVE A. UNGAR. JOSEPH F. KELLER 

